Magnetic resonance imaging signs of high intraventricular pressure - comparison of findings in dogs with clinically relevant internal hydrocephalus and asymptomatic dogs with ventriculomegaly

Abstract

BackgroundMagnetic resonance imaging (MRI) findings of canine brains with enlarged ventricles in asymptomatic dogs were compared to those in dogs with clinically relevant internal hydrocephalus, in order to determine the imaging findings indicative of a relevant increase in intraventricular pressure. Discrimination between clinically relevant hydrocephalus and ventriculomegaly based on MRI findings has not been established yet and is anything but trivial because of the wide variation in ventricular size in different dog breeds and individuals. The MRI scans of the brains of 67 dogs of various breeds, skull conformation and weight were reviewed retrospectively. Based on clinical and imaging findings, the dogs were divided into three groups: a normal group (n = 20), a group with clinically silent ventriculomegaly (n = 25) and a group with severe clinically relevant internal hydrocephalus (n = 22). In addition to the ventricle/brain-index, a number of potential subjective signs of increased intraventricular pressure were recorded and compared between the groups.ResultsThe ventricle/brain-index was significantly higher in dogs with relevant hydrocephalus (p < 0.001) and a threshold value of 0.6 was specified as a discriminator between internal hydrocephalus and ventriculomegaly. Other MR imaging findings associated with clinically relevant hydrocephalus were an elevation of the corpus callosum (p < 0.01), dorsoventral flattening of the interthalamic adhesion (p < 0.0001), periventricular edema (p < 0.0001), dilation of the olfactory recesses (p < 0.0001), thinning of the cortical sulci (p < 0.0001) and/or the subarachnoid space (p < 0.0027) and disruption of the internal capsule adjacent to the caudate nucleus (p < 0.0001).ConclusionA combination of the abovementioned criteria may support a diagnosis of hydrocephalus that requires treatment.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-015-0479-5) contains supplementary material, which is available to authorized users.

A case of acute acquired obstructive hydrocephalus in a cat with suspected ischaemic cerebellar infarct

“…5 Additionally, there was a narrowing of the cerebral sulci, obliteration of the subarachnoid space around the dorsal convexity of the cerebral hemisphere, elevation of the corpus callosum and overcrowding of the caudal fossa ( Figure 3). 5 Because of the peracute obstruction at the level of the fourth ventricle, the pressure in the ventricle would increase quickly and cause ventriculomegaly. The narrowing of the cerebral sulci and the obliteration of the subarachnoid space, seen in the MRI, are most likely the result of the high pressure in the ventricle and the low pressure in the arachnoid space.…”

“…The narrowing of the cerebral sulci and the obliteration of the subarachnoid space, seen in the MRI, are most likely the result of the high pressure in the ventricle and the low pressure in the arachnoid space. 5 Overcrowding of the caudal fossa is reported to be associated with increased ICP in hydrocephalic patients. 5 However, there is also the possibility that the overcrowding is simply an incidental finding that is often encountered in domestic shorthair cats.…”

“…Considering the changes observed on the MRI study, a hyper-acute territorial ischaemic infarction in the vascular territory of the right rostral cerebellar artery (RCA) 2-4 with acquired acute obstructive hydrocephalus was suspected. 5 Because the morphological changes observed upon MRI were indicative of increased intracranial pressure (ICP), cerebrospinal fluid collection was not performed.…”

Association between improvement of clinical signs and decrease of ventricular volume after ventriculoperitoneal shunting in dogs with internal hydrocephalus

“…The closely spaced walls of the temporal horns, third and fourth ventricle, or both, as well as olfactory and fastigial recesses were separated by CSF. In addition, thinning of the periventricular white matter compared to the brains of normal dogs, dorsal deviation of the corpus callosum, compression of the thalamic intermediate mass in the third ventricle, effacement of cerebral sulci, and diminution of the suprasellar cistern indicated an increase in IVP (Figure ). Supracollicular (quadrigeminal) cysts were diagnosed based on the finding of well‐defined space‐occupying lesions with fluid content intensity similar to CSF in a supracollicular location that did not enhance after contrast‐medium administration …”

Novel approach to magnetic resonance imaging of epileptic dogs — T2 relaxometry of the brain with emphasised hippocampus

“…Mild ventriculomegaly was present in two dogs in the control group (13.3%) and in 5 dogs in the epileptic group (16%) without any evidence of elevated intracranial pressure (Laubner et al, 2015). The findings were interpreted as breed-related normal findings (brachycephalic dogs) (Ryan et al, 2013).…”